Traditional washing industrial processes foresees the dipping of the product in sequence in washing tanks: normally, in the first tank a dipping takes place in aired water to support the separation of the product and the rough tainted material; in the following tanks, the product is dipped in progressively cleaner water. The passage of the product from one tank to the other takes place by the overflow with the help of a mesh conveyor belt that supports dripping via gravity before introducing it in to the next tank. To limit the transportation of the tainted material to the next tank as much as possible, sometimes also with the help of clean water showers, appropriate carter and protections determine the re-flow of the dripped water from the product to the origin tank.
At the end of the washing cycle (maximum 3 dips) the quantity of the biological and chemical material present on the to product under treatment will be, obviously, proportioned to the polluted content in the washing water of the last tank and it will also depend on the quantity of liquid that the product will carry within itself. The factor that determines the cleaning grade of the product submitted to treatment is therefore given by the level of water purity held in the last tank of the washing process.
In spite of the attention given by the equipment builders to limit the pouring of contaminated water from one tank to the next, the progressive pollution of the washing water appears inevitable and exponential due to the high concentration of contaminated elements constantly brought by the same product submitted to wash. Regarding the microbiological contamination the situation is even worsened with the passing of time by the bacterial multiplication in the dirty water where bacteria find a fertile sub-layer. According to the French law, that represents the best technical practice, the cooling of the washing water along the entire draw plain is necessary, a fact that involves high energetic costs. The injection of fresh water in the washing circuit naturally reduces the presence of pollution in the tanks, but only a total replacement cycle can allow restoring of initial cleaning conditions. Given the substantial water volumes held in the washing tanks, linked to the high water capacity necessary to forward the product along the manufacturing line, an accurate product cleaning implies a high consumption of fresh water. From this derives the low complex efficiency of these washing traditional system, that were conceived when water supply, waste water disposal and energy were much cheaper.
In regards to this, the situation is evolving, as, form one side, the plant management is increasingly under pressure concerning the restrictive laws that are increasing the quality and quantity controls, and on the other side consumers are becoming, every day, more demanding and careful in terms of healthiness guarantees of the final product and also more sensible to environment issues. Consequently there is an increase of production costs, not only the one coming from the water and the draining of the flows, but also the ones related to the often cleaning operations of the machineries and of the working environment. To contain water consumption in the traditional systems and of the consequent flows, it is often necessary to limit water renewal, that become inevitably a further worsening of the operative conditions with the consequence of higher use of chemical disinfection (mainly the active chlorine). The French regulation, which represents the benchmark for this application, also foresees that the working environment air temperature is kept very low with the aim of containing the development of polluting micro-organisms. This generates extremely uncomfortable conditions for the operators besides the further costs that this represents.
The technology proposed, based on the Modular Washing Unit (MWU), aims to give a positive reply on the above described problems; it aims, first of all, towards washing efficiency in terms of healthiness of the processed product, but it also aims to effectively reduce water consumptions and consequently the polluted flows, the use disinfecting chemical substances and energetic consumption, definitely limiting, with this, the overall environmental impact.